NCERT Solutions for Class 12 Physics Chapter 13 – Nuclei
NCERT Solutions for Class 12 Physics Chapter 13 – Nuclei help students understand the physics of the atomic nucleus – its composition, size, mass, binding energy, radioactivity, and nuclear reactions. Myclass24 presents these solutions with clear derivations and numerical approaches that are aligned with the CBSE exam pattern. This chapter is directly connected to Chapter 12 and builds on the idea of the atomic nucleus introduced by Rutherford. Also, get subject-wise NCERT Solutions for class 12, for all chapters of Physics, check NCERT Solutions for class 12 Physics.
Find the PDF of NCERT Solutions for Class 12 Physics Chapter 13 – Nuclei
Students can download the free PDF of NCERT Solutions for Class 12 Physics Chapter 13 – Nuclei from Myclass24. The PDF contains solved answers to all textbook questions, well-drawn diagrams wherever required, and explanations that match the CBSE marking scheme. Simply visit the Myclass24 website, navigate to Class 12 Physics, and find Chapter 13 to access or download the solution PDF at no cost. Having the PDF handy during revision allows you to study without an internet connection and make notes directly alongside the solutions.
Chapter 13 Details at a Glance
Detail | Information |
Chapter Number | 13 |
Chapter Name | Nuclei |
Subject | Physics |
Class | 12 |
Board | CBSE / NCERT |
Number of Exercises | 2 (Exercise + Additional Exercises) |
Total Questions | 31 |
Key Topics | Nuclear composition, binding energy, radioactivity, alpha/beta/gamma decay, nuclear fission and fusion |
Available Format | PDF (Free Download) |
What is Chapter 13 – Nuclei About?
Chapter 13 dives deep into the nucleus itself. The nucleus is made of protons and neutrons (collectively called nucleons). The number of protons is the atomic number Z, and the total number of nucleons is the mass number A. The radius of a nucleus is approximately R = R₀A^(1/3), which tells us nuclear density is roughly constant – a remarkable fact.
One of the most important concepts in this chapter is nuclear binding energy. When nucleons come together to form a nucleus, the total mass of the nucleus is slightly less than the sum of the masses of its constituent nucleons. This mass defect (Δm) is converted into binding energy using Einstein's formula: E = Δmc². A higher binding energy per nucleon means a more stable nucleus. The binding energy per nucleon curve peaks around iron (Fe-56), explaining why both fission of heavy nuclei and fusion of light nuclei release energy.
Radioactivity is a naturally occurring process in which unstable nuclei emit radiation to become more stable. There are three types: alpha decay (emission of a helium-4 nucleus), beta decay (emission of an electron or positron), and gamma decay (emission of a high-energy photon). The law of radioactive decay states that the number of nuclei decreases exponentially: N = N₀e^(−λt), where λ is the decay constant. Half-life (T₁/₂ = 0.693/λ) is the time for half the nuclei to decay.
Nuclear fission is the splitting of a heavy nucleus (like Uranium-235) into two lighter nuclei, releasing enormous energy – the basis of nuclear power plants and atomic bombs. Nuclear fusion is the combining of light nuclei (like hydrogen isotopes) to form a heavier nucleus, releasing even more energy per unit mass – the process powering the sun.
Myclass24's solutions for Chapter 13 include well-explained answers to all theoretical and numerical questions, helping students score confidently on this high-weightage chapter.
How to Use NCERT Solutions for Chapter 13 Effectively
Start by reading the relevant pages in your NCERT textbook and trying the questions on your own. Then cross-check with Myclass24's solutions to see where your approach differed. Pay attention to how formulae are applied, how diagrams are drawn, and how marks are allocated in multi-step problems. Make a separate notes page for key formulae and definitions from this chapter. Attempt past CBSE board papers and sample papers on Chapter 13 after completing the NCERT exercises. This cycle of reading, solving, and reviewing is the most reliable way to prepare.
FAQs for NCERT Solutions Class 12 Physics Chapter 13 Nuclei
The atomic nucleus is the dense central region of an atom containing protons and neutrons. This chapter explains how the nucleus accounts for most of an atom’s mass while occupying a very small volume. Students learn about nuclear composition, atomic number, mass number, and isotopes. Understanding nuclear structure is important because it forms the basis for studying radioactivity and nuclear reactions. Questions related to nuclear properties and composition are frequently included in board examinations. A strong understanding of the nucleus helps students grasp the principles governing atomic stability and nuclear energy.
Radioactivity is the spontaneous emission of particles or radiation from unstable atomic nuclei. This chapter explains how certain nuclei become more stable by releasing alpha particles, beta particles, or gamma rays. Students learn about radioactive decay, half-life, and decay laws. Understanding radioactivity is important because it has applications in medicine, industry, archaeology, and scientific research. Numerical problems involving decay calculations frequently appear in examinations. The study of radioactivity also helps students understand the natural processes occurring within unstable elements and radioactive substances.
Half-life is the time required for half of the radioactive nuclei in a sample to decay. This chapter explains how half-life is used to measure the rate of radioactive decay and determine the stability of radioactive substances. Students learn mathematical relationships involving decay constants and remaining quantities of radioactive material. Understanding half-life is important because it has practical applications in nuclear medicine, carbon dating, and nuclear power generation. Questions involving half-life calculations are common in board examinations and competitive entrance tests, making this concept highly important.
Nuclear energy is the energy released during nuclear reactions such as fission and fusion. This chapter explains how small amounts of mass are converted into large amounts of energy according to Einstein’s mass-energy relationship. Students learn the principles behind nuclear reactors and the processes occurring in stars. Understanding nuclear energy is important because it plays a significant role in electricity generation and scientific research. Questions comparing nuclear fission and fusion are frequently asked in examinations. This topic demonstrates how atomic nuclei can serve as powerful sources of energy.